1. Field of the Invention
The present invention relates to a vent assisted design assembly for increased wind resistance of membrane roofs using active roof vents and augmented perimeter attachment.
2. Brief Description of the Prior Art
Single-ply roofing systems using EPDM (ethylene propylene diene) rubber, chorosulphanated polyethylene, TPO (thermoplastic polyolefin), PVC (polyvinylchloride), and other synthetic single layer sheets as the top layer of water impervious material are especially advantageous for flat or low pitch roofs, such as found on large commercial buildings. When wind rolls over the edges of a roof, a vortex is created which is most intense along perimeter edges and particularly at corners. This vortex creates an uplift pressure which can cause a single-ply membrane to peel starting in the turbulent wind vortex areas of the perimeter edges. In the field-of-roof area inside the corners and perimeter, wind uplift is diminished.
All single-ply roofing systems have two main challenges:
Making seams via heat welding, adhesives, caulks and tapes; and, Designing a system that keeps the membrane on the roof in high wind. Everything done on a roof project is related to those two tasks, with most of the engineering and design being spent on the latter.
There are a number of techniques used to keep membranes on top of the roof. These include: (1) Stone Ballast—inexpensive but the weight added to the building is a concern; (2) Fully Adhered, i.e. gluing the membrane to the substrate using adhesives—expensive and there is growing concern over volatile organic compounds (VOCs) contained in the glue being released into the environment; (3) Mechanically Fastened—inexpensive, lightweight, lower VOC's but trapping moisture under the membrane and flutter fatigues are concerns and (4) Vented devices to equalize wind uplift pressure.
The Thomas L. Kelly, Roof Equalizer patent (U.S. Pat. No. 4,223,486) laid the foundation for using roof vents to equalize wind uplift. The patented vent was commercialized by the 2001 Company but the balance of the Kelly roof system was flawed. In the 2001 Company systems the membranes are mechanically fastened at the roof edge and glued for 24 or 30 inches at the corners and along the perimeter edges. Although the patented roof reduces wind uplift pressure, the corners and perimeter of the membrane tend to begin to flutter as a first stage of peeling as membranes shift and adhesives dry out which can result in catastrophic roof failure. Most of the engineering and design effort in the single-ply roof industry after Thomas L. Kelly's passive vent has been focused on differing vent designs such as turbine vent systems like those made by Burke Industries or Venturi vents licensed by Virginia Tech Intellectual Properties, Inc. Neither of which have addressed the need for increased perimeter attachment or for identifying the most effective location for the vent.